The Checkit Game is suitable for all ages because you can choose the type of numbers and the operation that you will use.

You can play this game with different sets of numbers like whole numbers or integers, fractions or decimals and with  (1) addition and subtraction or with (2) multiplication and division, whichever you choose. You can play with algebraic expressions and other types of entries in the boxes.

Start with 3 entries and 3 empty boxes. The numbers on the edges of the triangle are the sum in Game 1 and the same numbers could be the product of the numbers at the vertices in Game 2.

So in this example Game 1 would have 143, 187 and 154 on the edges and Game 2 would have 4840, 8712 and 5445 on the edges.

Here are the rules for the Checkit game for 2 players or teams:

1. The players must agree on the types of entries in the boxes to be used in the game. For example the entries could be whole numbers or integers, or rational numbers, or powers of 2, 3, 4 and 7 or, for young learners, the numbers could be small, just 0 to 10 at the vertices. Or the entries could be algebraic expressions.
2. The players must agree on the operations to be used in the game.
3. Flip a coin to decide who goes first.
4. Players take it in turns to fill in an empty box.
5. Players check if the numbers entered are correct. If a player makes a mistake, and is challenged by an opponent before the opponent enters another number, then he loses the game and his opponent wins a point.
6. When all 6 boxes have entries in them both players check and if there are any mistakes then both players lose a point, if everything is correct, both players win a point.
7. The first player to score 5 points wins the game.
Here is another example where the operations are addition and subtraction. What numbers go in the empty boxes? Click here for the answer.

1. The players must agree on the type of entries, on the operation to be used and on the time allowed.
2. Both players draw a Checkit frame and fill in 3 of the 6 numbers.
3. They swop frames and, in the given, complete the puzzle set by their opponent  by filling in the other 3 entries. They score a point for each   correct entry. It must always be possible to complete the 6 entries and players can challenge each other if they think their opponent has made a mistake or made the puzzle impossible to complete.
4. Play 3 rounds and the player with the highest score wins.

What similarities and differences can you see between The Checkit Game with Addition and Polycircles  https://aiminghigh.aimssec.ac.za/polycircles/ and The Triangle Midpoints Problem https://aiminghigh.aimssec.ac.za/triangle-midpoints/?